Archive

28 September 2011, Volume 18 Issue 3 Previous Issue    Next Issue
---
Research Paper
Review or Special Topic
Short Communication


For Selected:

Download Citations EndNote Ris BibTeX

Toggle Thumbnails

Research Paper

Select

Differential Expression of Two Cytosolic Ascorbate Peroxidase and Two Superoxide Dismutase Genes in Response to Abiotic Stress in Rice Shigeto MORITA, Shinya NAKATANI, Tomokazu KOSHIBA, Takehiro MASUMURA, Yasunari OGIHARA, Kunisuke TANAKA 2011, 18(3): 157-166.  Abstract ( )   PDF (29444KB) ( )   Superoxide dismutase (SOD) and ascorbate peroxidase (APX) play central roles in the pathway for scavenging reactive oxygen species in plants, thereby contributing to the tolerance against abiotic stress. Here we report the responses of cytosolic SOD (cSOD; sodCc1 and sodCc2) and cytosolic APX (cAPX; OsAPX1 and OsAPX2) genes to oxidative and abiotic stress in rice. RNA blot analyses revealed that methyl viologen treatment caused a more prominent induction of cAPXs compared with cSODs, and hydrogen peroxide treatment induced the expression of cAPXs whereas cSODs were not affected. These results suggest that cAPXs play more important roles in defense against oxidative stress compared with cSODs. It is noted that cSODs and cAPXs showed coordinate response to abscisic acid treatment which induced both sodCc1 and OsAPX2. However, cSODs and cAPXs responded differentially to drought, salt and chilling stress, which indicates that cSOD and cAPX genes are expressed differentially in response to oxidative and abiotic stress in rice.Abstract: Superoxide dismutase (SOD) and ascorbate peroxidase (APX) play central roles in the pathway for scavenging reactive oxygen species in plants, thereby contributing to the tolerance against abiotic stresses. Here we report the responses of cytosolic SOD (cSOD; sodCc1 and sodCc2) and cytosolic APX (cAPX; OsAPx1 and OsAPx2) genes to oxidative and abiotic stresses in rice. RNA blot analyses revealed that methyl viologen treatment caused a more prominent induction of cAPXs compared with cSODs. Hydrogen peroxide treatment induced cAPXs whereas cSODs were not affected. These results suggest that cAPXs play more important roles in defense against oxidative stress compared with cSODs. It is noted that cSODs and cAPXs showed coordinate response to abscisic acid treatment by which sodCc1 and OsAPx2 were both induced. However, cSODs and cAPXs responded differentially to drought, salt, and chilling stresses, which indicates that cSOD and cAPX genes are expressed differentially in response to oxidative and abiotic stresses in rice.

Select

Systematic Identification of Rice ABC1 Gene Family and Its Response to Abiotic Stress GAO Qing-song, ZHANG Dan, XU Liang, XU Chen-wu 2011, 18(3): 167-177.  Abstract ( )   PDF (116081KB) ( )   Members of the activity of bc1 complex (ABC1) family are protein kinases that are widely found in prokaryotes and eukaryotes. Previous studies showed that several plant ABC1 genes participated in the abiotic stress response. Here, we present the systematic identification of rice and Arabidopsis ABC1 genes and the expression analysis of rice ABC1 genes. A total of 15 and 17 ABC1 genes from the rice and Arabidopsis genomes, respectively, were identified using a bioinformatics approach. Phylogenetic analyses of these proteins suggested that the divergence of this family had occurred and their main characteristics were established before the monocot-dicot split. Indeed, species-specific expansion contributed to the evolution of this family in rice and Arabidopsis after the monocot-dicot split. Intron/exon structure analysis indicated that most of the orthologous genes had similar exon sizes, but diverse intron sizes, and the rice genes contained larger introns, moreover, intron gain was an important event accompanying the recent evolution of the rice ABC1 family. Multiple sequence alignment revealed one conserved amino acid segment and four conserved amino acids in the ABC1 domain. Online subcellular localization predicted that nine rice ABC1 proteins were localized in chloroplasts. Real-time RT-PCR established that the rice ABC1 genes were primarily expressed in leaves and the expression could be modulated by a broad range of abiotic factors such as H2O2, abscisic acid, low temperature, drought, darkness and high salinity. These results reveal that the rice ABC1 gene family plays roles in the environmental stress response and specific biological processes of rice.

Select

Molecular Mapping of QTLs for Yield and Related Traits in Oryza sativa cv Swarna x O. nivara (IRGC81848) Backcross Population B. P. MALLIKARJUNA SWAMY1,,K. KALADHAR, M. S. RAMESHA, B. C. VIRAKTAMATH, N. SARLA 2011, 18(3): 178-186.  Abstract ( )   PDF (22574KB) ( )   Advanced backcross QTL analysis was used to identify QTLs for seven yield and yield-related traits in a BC2F2 population from the cross between a popular Oryza sativa cv Swarna and O. nivara IRGC81848. Transgressive segregants with more than 15% increased effect over Swarna were observed for all the traits except days to heading and days to 50% flowering. Thirty QTLs were detected for seven yield and yield-related traits using interval and composite interval mapping. Enhancing alleles at 13 (45%) of these QTLs were derived from O. nivara, and enhancing alleles at all the QTLs for stem diameter and rachis diameter were derived from O. nivara. Three stem diameter QTLs, two rachis diameter QTLs and one number of secondary branches QTL identified by both Interval and composite interval mapping contributed more than 15% of the total phenotypic variance. The QTL epistasis was significant for stem diameter and plot yield. The most significant QTLs qSD7.2, qSD8.1 and qSD9.1 for stem diameter, qRD9.1 for rachis diameter and qNSB1.1 for number of secondary branches are good targets to evaluate their use in marker-assisted selection. O. nivara is a good source of novel alleles for yield related traits and reveals major effect QTLs suitable for marker-assisted selection.

Select

Identification of QTL Affecting Protein and Amino Acid Contents in Rice ZHONG Ming, WANG Ling-qiang, YUAN De-jun, LUO Li-jun, XU Cai-guo, HE Yu-qing 2011, 18(3): 187-195.  Abstract ( )   PDF (3789KB) ( )   The phenotypes of protein and amino acid contents were measured in an F9 recombinant inbred line population derived from a cross between Zhenshan 97B and Delong 208. A total of 48 and 64 QTLs were identified in 2004 and 2005, respectively. The contribution of each QTL to the phenotypic variation ranged from 4.0% to 43.7%. Most QTLs co-localized, forming 29 QTL clusters on the chromosomes with three major ones detected in both years, which were mapped on chromosomes 1, 7 and 9, respectively. The two QTL clusters for amino acid content, qAa1 and qAa7, influenced almost all the traits with the allele from Zhenshan 97B, and the third QTL cluster for amino acid content, qAa9, increased the lysine content with the allele from Delong 208. A wide coincidence was found between the QTL detected under this study and the loci involved in amino acid metabolism pathways in nitrogen assimilation and transport, or protein biosynthesis. The results would facilitate the identification of candidate genes and could be used in marker-assisted selection for the favorable allele in rice quality improvement.

Select

Mining Applicable Elite Alleles of Growing Duration, Plant Height and Panicle Number per Plant by Conditional QTL Mapping in Japonica Rice JIANG Jian-hua, ZHAO Qi-bing, LIU Qiang-ming, CHEN Lan, CHEN Fu-long, QIAO Bao-jian, HONG De-lin 2011, 18(3): 196-203.  Abstract ( )   PDF (775KB) ( )   Unconditional QTL mapping and conditional QTL mapping were conducted for growing duration (GD), plant height (PH) and effective panicle number per plant (PN) using a recombinant inbred line (RIL) population derived from a cross between Xiushui 79 and C Bao in japonica rice (Oryza sativa L.). The RIL population consisted of 254 lines was planted in two environments, Nanjing and Sihong, Jiangsu Province, China. Results showed that additive effects were major in all of QTLs for GD, PH and PN detected by the two methods, and the epistatic effects explained a small percent of phenotypic variation. No interactions were detected between additive QTL and environment, and between epistatic QTL pairs and environment. After growth duration was adjusted to an identical level, RM80-160bp was detected as an applicable elite allele for PN, with an additive effect of 0.71. After effective panicle number per plant was adjusted to an identical level, RM448-240bp was detected as an applicable elite allele for GD (shorten), with an additive effect of 4.64. After plant height was adjusted to an identical level, RM80-160bp was detected as an applicable elite allele for PN, with an additive effect of 0.62, and RM448-240bp was detected as an applicable elite allele for GD, with an additive effect of 3.89. These applicable elite alleles could be used to improve target traits without influencing the other two traits.

Select

Quantitative Trait Loci Associated with Pollen Fertility under High Temperature Stress at Flowering Stage in Rice (Oryza sativa) XIAO Ying-hui, PAN Yi, LUO Li-hua, DENG Hua-bing, ZHANG Gui-lian, TANG Wen-bang, CHEN Li-yun 2011, 18(3): 204-209.  Abstract ( )   PDF   High temperature stress (HTS), an increasingly important problem in rice production, significantly reduces rice yield by reducing pollen fertility and seed setting rate. Breeding rice varieties with tolerance to HTS at the flowering stage is therefore essential for maintaining rice production as the climate continues to become warm. In this study, two quantitative trait loci (QTLs) underlying tolerance to HTS were identified using recombinant inbred lines derived from a cross between an HTS-tolerant rice cultivar 996 and a sensitive cultivar 4628. Pollen fertility was used as a heat-tolerance indicator for the lines subjected to HTS at the flowering stage in field experiments. Two QTLs that affected pollen fertility, qPF4 and qPF6, were detected between RM5687 and RM471 on chromosome 4, and between RM190 and RM225 on chromosome 6, by using the composite interval mapping (CIM) analysis. The two QTLs explained 15.1% and 9.31% of the total phenotypic variation in pollen fertility, and increased the pollen fertility of the plants subjected to HTS by 7.15% and 5.25%, respectively. The positive additive effects of the two QTLs were derived from the 996 alleles. The two major QTLs identified would be useful for further fine mapping and cloning of these genes and for molecular marker-assistant breeding of heat-tolerant rice varieties.

Select

High Temperature at Grain-filling Stage Affects Nitrogen Metabolism Enzyme Activities in Grains and Grain Nutritional Quality in Rice LIANG Cheng-gang, CHEN Li-ping, WANG Yan, LIU Jia, XU Guang-li, LI Tian 2011, 18(3): 210-216.  Abstract ( )   PDF (1669KB) ( )   Rice plants would more frequently suffer from high temperature (HT) stress at the grain-filling stage in future. A japonica rice variety Koshihikari and an indica rice variety IR72 were used to study the effect of high temperature on dynamic changes of glutamine synthetase (GS) activity, glutamate synthase (GOGAT) activity, glutamic oxalo-acetic transminase (GOT) activity, glutamate pyruvate transminase (GPT) activity in grains and grain nutritional quality at the grain-filling stage. Under HT, the activities of GOGAT, GOT, GPT and soluble protein content in grains significantly increased, whereas GS activity significantly decreased at the grain-filling stage. In addition to the increase of protein and amino acids contents, it was suggested that GOGAT, GOT and GPT in grains played important roles in nitrogen metabolism at the grain-filling stage. Since the decrease of GS activity in grains did not influence the accumulations of amino acids and protein, it is implied that GS might not be the key enzyme in regulating glutamine content in grains.

Select

Effects of Mulching Mode on Canopy Physiological, Ecological Characteristics and Yield of Upland Rice ZHANG Yu-zhu, LIU Yang, ZENG Xiang, CHEN Kai-lin, HUANG Ze-hui, XIE Hong-ke 2011, 18(3): 217-223.  Abstract ( )   PDF (1567KB) ( )   The effects of mulching mode on population physiology and ecology of rice were studied using a combination P88S/1128 as the material under three mulching cultivation modes including plastic film mulching, straw mulching and liquid film mulching, as well as bare cultivation (control). The results indicated that mulching mode had significant effects on micro-meteorological factors and individual growth of rice, as shown by an increase of relative humidity, a better internal micro-meteorological environment of rice population, a significant reduction under the rice canopy temperature, especially during high-temperature periods. Rice plants under mulching cultivation conditions displayed a stronger transpiration and lower leaf temperature, thereby improving the ability of anti-high temperature stress and markedly increasing the photosynthetic rate. Furthermore, the yield components of rice were significantly optimized under mulching cultivation, of which with plastic film mulching displayed the highest grain number per panicle and seed-setting rate, and a yield increase of 16.81% compared with the control; and with straw mulching displayed an increase of effective panicle number and a 9.59% increase of total yield compared to the control.

Select

Realistic Simulation of Rice Plant Ding Wei-long, Zhang Yu-ping, Zhang Qian-yuan, Zhu De-feng, Chen Qi 2011, 18(3): 224-230.  Abstract ( )   PDF (1540KB) ( )   The research of virtual crop modeling has become a hotspot in the field of digital agriculture. The existing research results of virtual modeling of rice plant, however, is far from perfection compared to that of other crops due to its complex structure and growth process. This paper presents techniques to visually simulate the architecture of rice plant and its growth process based on the analysis of the morphological characteristics at different stages. Firstly, the simulation of geometrical shape, the bending statuses and the structural distortion of rice leaves is conducted. Then, by using an improved model of bending deformation, the curved patterns of panicle axis and various types of panicle branches are generated, and the spatial shape of rice panicle is therefore created. Parametric L-system is employed to generate its topological structures, and Finite-state automaton is adopted to describe the development of geometrical structures. Finally, the computer visualization of three-dimensional morphologies of rice plant at both organ and individual levels is achieved. The experimental results showed that the proposed methods of modeling the three-dimensional shapes of organs and simulating the growth of rice plant are feasible and effective, and the generated three-dimensional images are realistic.

Review or Special Topic

Select

Functions of Phytochrome in Rice Growth and Development GU Jian-wei, LIU Jing, XUE Yan-jiu, ZANG Xin, XIE Xian-zhi 2011, 18(3): 231-137.  Abstract ( )   PDF (751KB) ( )   Phytochrome family mainly senses red and far-red light to regulate a range of developmental processes throughout the life cycle of plants. Rice phytochrome gene family is composed of three members known as PHYA, PHYB and PHYC. It has been elucidated that individual phytochromes display both unique and overlapping roles in rice photomorphogenesis by characterization of all rice phytochrome mutants including single mutants, all combinations of double mutants as well as triple mutants. Based on the published data and authors’ ongoing studies, current knowledge of rice phytochrome functions in regulating seedling de-etiolation, root gravitropic response and elongation, plant architecture, flowering time and fertility is summarized. Additionally, the important issues in the field of rice phytochromes are proposed.

Short Communication

Select

Genetic Analysis and Preliminary Mapping of Two Recessive Resistance Genes to Brown Planthopper, Nilaparvata lugens St?l in Rice HOU Li-yuan, YU Ping, XU Qun, YUAN Xiao-ping, YU Han-yong, WANG Yi-ping, WANG Cai-hong, WAN Guo, TANG Sheng-xiang, PENG Suo-tang, WEI Xing-hua 2011, 18(3): 238-242.  Abstract ( )   PDF (8207KB) ( )   An F2 population derived from the cross of WB01, an introgression line resistant to brown planthopper (BPH) originated from Oryza rufipogon Griff. and a susceptible indica variety 9311, was developed for genetic analysis and gene mapping. The population with 303 F2:3 families was genotyped by 141 simple sequence repeat (SSR) markers and used for gene mapping. Two softwares, Mapmaker/Exp 3.0 and Windows QTL Cartographer V2.0 were applied to detect QTLs. Totally, two QTLs resistant to BPH, named temporarily as bph22(t) and bph23(t), were identified to locate on chromosomes 4 and 8, individually had LOD values of 2.92 and 3.15, and explained 11.3% and 14 .9% of the phenotypic variation, respectively.